Keith Treschman published this thesis about starspots on active young stars as part of his Masters of Science studies.


Young solar-type stars inform us about the early evolution of objects that form a major component of the stellar population of our galaxy. Single active young solar-type stars close to the Sun’s mass also provide us with proxies for the Sun’s early history, its activity and underlying magnetic dynamo. The active young solar-type star AH Lep provides a convenient target to image its magnetic activity in detail.

AH Lep is of particular interest because of its relatively modest rotation rate (v sin i = 28 km s-1) compared with other previously studied active stars; in other words, this star represents the opportunity to study the effects of rotation on the dynamo of young solar-type stars.

This thesis investigates the starspot features and magnetic field of AH Lep using the techniques of Doppler and Zeeman Doppler Imaging, resulting in a tomographic map of the star and magnetic field detections.

In contrast to the large polar spot features of more rapidly rotating active solar-type stars, mid-latitude starspots predominate on AH Lep. At the time of observation at least, AH Lep displayed little in the way of a polar spot and instead showed large spot features more reminiscent of the Sun today than the polar spot dominated appearance of rapid and ultrarapid rotators. Total spot coverage (3.3%) is not small but is significantly less than that of rapid rotators.

The magnetic field of AH Lep was detected in a number of observations and a tentative magnetic map was constructed. More observations under the most favourable conditions are needed to investigate more fully the magnetic topology of the star.


Treschman, Keith. (2010). Starspots on the active young solar-type star AH Lep. MSc Thesis. University of Southern Queensland